Speed-regulating system



L. w. THOMPSON. SPEED REGULATING SYSTEM.

APPLICATION FILED NOV-26 1920- Patented J an. 10, 1922.

In\/ento1-'- Louis W Thomps by /%V M His Attorn y UNITED STATES sis-TEN orrics.

LOUIS W. THOMPSOhL OF SCHENECTA' DY, NEW YGRK, ASSIGNOB T0 GENERAL ELEC- TRIO COMPANY, A CORPORATION 01? NE YORK.

SPEED-REGULATING SYSTEM.

Specification of Letters Patent.

Patented J an. 10, 1922.

Application fi led November 26, 1920. Serial No. 426,363.

To (ZZZ whom it may concern:

Be it known that I, LOUIS .V. TrroMrsoN, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State ofNew York, have invented certain new and useful Improvements in Speed-Regulating Systems, of whichthe following is a specification.

My invention relates to speed regulating systems for direct current motors, and particularly to systems in which the setting of the regulator can be adjusted so that it will maintain the speed of the motor constantat different values.

' One object of my invention is to provide an arrangement whereby the speed of the motor may be maintained constant over a much greater range than it has been possible to maintain the speed constant with any of the arrangements used heretofore.

Another object of my invention is to provide an arrangement whereby the speed of the motor having a large field current may be maintained constant by. means of a vibratory regulator over a wide range, without subjecting the contacts of the regulator to undue arcing and burning.

Another object of my'invention is to provide means for ad ust1ng simultaneously the setting of the regulator to change the speed to be maintained constant and the pro- I portion of the total field current controlled by the regulator so that for all settin of the regulator it operates over substantially the same portion of its working range in maintaining the speed of the motor constant.

My invention will be better understood from the following description taken in connection with the accompanying drawing, and its scope will be pointed out in theappended claims. 7

Referring to the drawing, Fig. 1 is a diagram illustrating one embodiinent'ofmy invention; and Fig. 2 is a diagram illustrating a modification of the arrangement shown in Fig. 1. v

Referring to Fig. 1 of the drawing, 1 represents a source of directcurrent which is supplied to a motor 2, the speed of which is to be maintained constant. The motor is provided with an exciting circuit comprising the field windings 3 and 4.- which may be supplied with current from any suitable source. In the drawing, 1 have shown the windings as being connected in parallel across the terminals of an exciter 5, but it will be evident that if it were so desired these windings might be supplied with current from separate sources or from the source 1 instead of beine separately excited.

Tn the circuit of the ield winding 41 I provide a. resistance 7, the effective value of: which is controlled by a regulator 9, which may. be any. one of the well-known types of vibratory regulators, so as to vary the field of the motor to maintain the motor speed constant. It will be evident however that any other suitable regulating means may be used to control the current in the field winding 1 to maintain the motor speed in the circuit of the field winding so that the solenoid 12 is supplied with current proportional to the current flowing through the field winding 4.. The solenoid 13 is supplied with cu rent from the pilot generator 15 driven by the motor 2 and shown in the drawing as being connected to the same shaft. The pilot generator may be of any suitable type, but preferably of the magneto type and so arranged that the voltage thereof is proportional to the speed of the motor. Controlled by the contacts 10 and 11 of the regulator 9 is a relay 17 which acts upon a spring-held armature 18. This armature 18 is arranged to short-circuit the resistance 7 when not acted upon by the relay. The relay' 17 is provided with the winding 19 which is connected directly across the terminals of the exciter 5 and a difi'erential windinc; 21 which is adapted to be connected a ross the terminals of the enciter 5 when the contacts 10 and 11 are closed. When both of the windings 19 and 21 are energized the armature 18 occupies the position shown in the drawing. thereby short-circuiting theresistance 7, but when only the winding 19 is energized the armature 18 is attracted by the relay and the resistance 7 is inserted in the circuit of the field winding 1.

In circuitwith the solenoid 13 and the generator I provide an adjustable resistance- 23 so that the setting of the regulator can be changed when it is desired to change the 7 speed to be maintained constant by the regulator. The movable arms of the adjustable resistances 6 and 23 are preferably connected. togetherin any desired manner; as bya rod.

24 so that both of the resistances may be adjusted simultaneously. The steps of the resistances 6 and 23 are so designed that when the resistance 23 is variedtochange the setting of the regulator, the resistance'G is adjusted to vary the proportion of the total field" current flowing through the field winding 3 so that for all settings of the regulator V it operates over substantially the same portion'oi' itsworkingrange in maintaining the speed'of'the motor constant. It is well known that the best regulation is obtained avith a vibratory regulator'when the regulator is working over that portion of its range where the contacts of'the vibratory rerun at the new speed determined by the-new setting of the regulator is produced inthat portion of theexciting circuit controlled by the resistance 6. Therefore, substantially no change in. the current through the portion of the exciting circuit controlled byvthe regulator .isproduced by changing the setting of the regulator. Consequently, with this arrangement I am able to maintain the. speed of a motor constant over a much greater range than any arrangement used heretofore in which the amount of current controlled by the regulator is'changed each time the setting of the regulator is changed. Furthermore,

since the currentifiowing throughthep'ortionof the exciting circuit controlled by the regulator is only a'portion of the total exciting current, and ordinarily is only a very small proportion, it is evident that my invention provides an arrangement for controlling the speed of motors having very large field currents.

V regulator may be used to maintain the speed of a motor'constant overa wide range without sub ecting the contacts of the regulator to undue arcing and burning. V

The operation of the arrangement shown in Fig. 1 is as follows: Let 1t be assumed that the motor is running, that the exciter 5 is supplying current tothe field windings 3 and 1 and thatthe resistances 6 and 23 have been adjusted to maintain the speed of the motor Therefore, an ordinary vibratory at a predetermined value, and that the contacts 10 and 11 are closed.

Ifthe speed of the motor tends to vary from this predetermined value, due, for example, to a. change in load or a change in voltage of the source 1-, the voltage of the pilot generator lavaries, thereby changing the current flowing through the solenoid 13 whereuponthe regulator 9 operates tochange the effective value of current flowing through field winding 4 to restore the speed of the motor 'to the predetermined value. For example,- if'thespeed of the motor 2 decreases the voltage of the pilot generator 15 de-' creases'thereby causing contact 11 to move out of engagement with contact" 10. The opening of thecontact's lO and 11 deenergizes the winding 21 of the relay 17 so that the relayattracts the armature 18 thereby inserting the resistance 7 in the circuit of the field winding 1 The motor-field is thereby decreased,'resultingin an increase in the speed 'ofthe motor. As soon as thespeed of the the contact 11 in response to a decrease in the fieldourrent ofthe motor due to the opening ofthe contacts 10 and 11 and will be moved out of engagement withcontact 11 in response to an increase in the field current of the motor due tothe closing of the contacts '10 and ll. Thisoperationof contact 10 is obtained by connecting the solenoid 12 so that the current therein varies in accordance with the current in the field winding 1. With this arrangement, it will beobserved that the contact 10 will be in a state of constant'vibration since the current through the field winding 4; is constantly varying a small amount due to the action ofthe'fioating contacts-10 and 11. I 7

- With the regulator arranged to holdconstantispeed at any particular value,' the current in the solenoid 18 supplied from the pilot generator 15 is practically constant. Ifitis desired to adjust the regulator to hold another value of constant speed this is accomplished'by moving the rod 24 in the proper direction, thereby simultaneously varying the resistances 6 and 23. As stated above the resistance 6 is so adjusted that when the motoris running at the new speed determined; by the setting-of the regulator, the regulator 9'operates oversubstantially the same portion of its working range in maintaining the speed constant as it did when the motor was running at its former speed.

In the modification shown in Fig. 2, the motor 2 is provided with only one lield winding 4 and the resistances 6 and 7 are connected in multiple. In this arrangement the steps of the resistances 23 and *3 are so designed that when the resistance 23 is ried to change the setting of the regulator the resistance 6 is varied to change the citing current of the motor and the proportion thereof flowing through the resistance 6 so that for all settings or the regulator it will operate over substantially the same portion of its working range in maintaining the speed of the motor constant. It will be evident that with this arrangement the resistance 6 is so designed that as the necessary changes in the current through the field winding t are produced to cause it to run at the new speed determined by the setting of the regulator, substantially no change in the amount of current through the portion of the exciting circuit comprising the resistance 7 and contacts 10 and 11. It is believed that the operation of the modification shown in Fig. 2 will be obvious from the description of the operationof the arrangement shown in Fig. 1 and therefore a detail description thereof is deemed unnecessary.

It will be apparent that while 1 have shown and described two modifications oi my invention that various other modifications and changes may be made without departing from the true scope and spirit of my invention, and I, therefore, wish it to be understood that I do not desire to be limited to the exact arrangement shown, but seek to cover in the appended claims all those modifications and changes which fall within the true scope and spirit or my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is

'1. In combination, a direct current motor, an exciting circuit for said motor, a regulator for controlling the current in one portion of said exciting circuit to maintain the speed of the motor constant at desired value, and means arranged to be operated simultaneously to vary the setting of said regulator to change the speed to be maintained constant and the proportion of the total field current flowing through another portion of said exciting circuit so that for all settings of the regulator it operates over substantially the same portion of its working range in maintaining the speed of the motor constant. I

2. In combination, a direct current motor having two field windings, a regulator for controlling the current in one oi? said field windin s to maintain the sneed oi the 1110- tor constant at any desired value, and means arranged to be operated simultaneously to vary the settingo'f said regulator to change the speed to be maintained constant and the srine portion of its working range in maintaining the speed of the motor constant.

In combination, a direct current motor, an exciting circuit for said motor having two portions thereof connected in multiple, a generator driven by said motor, an adjustable resistance connected in one of said portions or said exciting circuit, a regulator for controlling the current in the other portion of said exciting circuit to maintain the speed of the motor constant at any desired value, comprising a resistance connected in the last-mentioned portion oi"- said exciting circuit, and a solenoid supplied with current from said generator controlling a short circuit around said resistance, an adjustable resistance connected in the circuit of said generator and solenoid, and means arranged to be operated simultaneously to vary said lastmentioned adjustable resistance to change the speed to be maintained constant by said regulator and said first-mentioned adjustable resistance to change the proportion of the total exciting current flowing therethrough e that for all settings of the regulator it operates over substantially the same portion of its working range in maintainingthe speed of the motor constant.

In combination, a direct current motor having two field windings connected in multiple, generator driven by said motor, an adjustable resistance connected in series with one of said field windings, a regulator for cont 1 'ng the current in the other of said field vindings maintain the speed or" the motor constant at any desired value, com rising a resistance connected in series with said last-mentioned field winding, and a solenoid supplied with current from said generator controlling a shortcircuit around said resistance, an adjustable resistance conn the circuit of said generator and over subworking con 01 the motor 5. in combination, direct current motor, exciting circuit for said motor having two pornons thcreoi connected in multiple,

a generator driven by said motor, an adjustable resistance in circuit with one of said portions of said exciting circuit, a second resistance connected in the other portion of said exciting circuit, a relay for short-circuiting said second resistance, a pair of contacts controlling said relay, a solenoid controlling one of said contacts supplied with current proportional to the current in said last mentioned portion of said exciting circuit, another solenoid controlling the other one of said contacts supplied with current from said generator, an adjustable resistance in circuit with said last-mentionedsolenoid and said generator, and means arranged to vary simultaneously said adjustable resistances.

6. In combination, a direct current motor having'two field windings connected in multiple, a generator driven bysaid motor, an

tioned field winding, another solenoid controlling the other-oneof said contacts'supadjustable resistance in circuit with said last-mentioned solenoid and said generator, and means for simultaneously adjusting said adjustable resistances. V

In witness whereof, I have hereunto set my hand this 24th day of November, 1920,

LOUIS THOMPSON, V

plied with current from said generator, an r 

